Papio cynocephalus is a broadly distributed species, ranging through most of Eastern Africa south of the equatorial rain forests. These baboons occur in Botswana, Kenya, Malawi, Somalia, Tanzania, Zaire, and Zimbabwe. They are found east of the Luangwa in Zambia, in Northern Mozambique and throughout most of Tanzania.
These monkeys are highly sexually dimorphic. Males weigh around 23 kg and females around 12 kg. The head and body length ranges between 508 and 1,143 mm, with the tail adding an additional 456 to 711 mm to the total length. These animals have 32 teeth. The first lower premolar is modified and serves as a hone for the upper canine tooth. Males have large canine teeth, whereas the teeth of females are much smaller. There is significant geographic variation in average body size and skull size, as well as in the texture of pelage. The three forms most often described are Ibean baboons, Kinda baboons, and "typical" yellow baboons. (Groves, 2001; Jolly, 1993; Napier and Napier, 1985; Nowak, 1999; Primate Info Net, 2000)
The orientation of the face in yellow baboons is normal, helping to distinguish them from Papio ursinus which has a downwardly flexed face. The post-orbital constriction of these animals is less pronounced than in anubis and chacma baboons. Ibean yellow baboons have large skulls. Typical yellow baboons have medium to large skulls. Kinda baboons are noted for their greatly reduced cranial size, associated smaller teeth, and weakly expressed temporal lines. (Jolly, 1993)
Pelage is characteristically a yellowish-brown. This overall color is produced by individual hairs which are yellow-brown for most of their length but have a black tips. In typical yellow baboons, both males and females are unmaned. However, in the Ibean form of this species, males have a weakly expressed mane. It is not at all comparable to the large mane found in Papio hamadryas, Papio anubis, and Papio papio. The head has a prominent crest on the top, produced by the longish hairs which grow upward toward the crest. This helps to distinguish this species from P. anubis which has a "flat" head. The pelage of typical and Kinda forms of this species is straight. The hair of Kinda baboons is reported to be very silky in texture. In contrast, the hairs of Ibean baboons are wavey and coarser than those of the other yellow baboons. All yellow baboons have hands and feet that are the same color as the rest of the body, and silver-colored fringes on the hands and feet. (Groves, 2001; Jolly, 1993; Napier and Napier, 1985; Nowak, 1999; Primate Info Net, 2000)
Tail shape varies geographically. The tail of Ibean baboons resembles that of P. anubis, with the proximal portion extending straight out from the rump, and the distal 3/4 falling limp, as if the tail has been broken. Kinda baboons have a gracefully arched tail. Typical yellow baboons generally have the bent phenotype, but are variable, with some individuals showing the arched tail morphology. (Groves, 2001; Jolly, 1993)
In Ibean and typical yellow baboons, the natal pelage is black. This fur is replaced by the typical yellowish-brown by about 6 months of age. In sharp contrast, the natal coat of Kinda baboons is a reddish-brown color. (Jolly, 1993)
It should be noted that as in many other social animals, there can be other factors which affect a male’s mating success. For example, males may form alliances with other males, subverting the normal dominance hierarchy. Two males, neither of whom can dominate a third male alone, may join forces. As a coalition, these males may succeed in securing access to a sexually receptive female. Such coalitions are reciprocal, and typically occur between pairs of older males who are well acquainted with one another through mutual tenure in a troop. (Melnick and Pearl, 1987; Smuts, 1987a)
Males also follow a strategy of developing "friendships" with females This enhances their opportunities to mate. In these friendships, males groom, share food, and have strong affiliative ties with particular females and their offspring. It is common for males to defend their female friends during agonistic encounters with other females, and with other males. These associations are not confined to the period during which females are sexually receptive, but span the entire gamut of the female’s reproductive life—including pregnancy, lactation, and time spent cycling. Females exhibit a preference for mating with their male friends, and therefore make consortships with their male friends more likely. In addition, because females prefer their friends as mates, they are more likely to cooperate with them in the maintenance of a consortship than they are to cooperate with other, less favored, males. (Melnick and Pearl, 1987; Smuts, 1987a)
Reproduction in (Melnick and Pearl, 1987)is related to the social structure of this species. Yellow baboons live in multi-male, multi-female troops. Mating is polygynandrous, with both males and females mating with multiple partners. Most matings occur during consortships. Consortships arise when a male, through aggression toward potential rivals, is able to maintain exclusive sexual access to a female. Females may consort with multiple males while they are sexually receptive, although they consort with only one male at a time. Because it is apparently easier for a male to maintain exclusive access to a female if the female is cooperative, there is a significant amount of female mate choice, with females preferring some partners over others.
Females characteristically have an estrous cycle of 32 days in length, however, cycle length varies between individuals and between populations. At the Tana River National Primate Reserve in Kenya, primiparous females had the longest cycles, averaging 44 days, and multiparous females had the shortest cycles, averaging 37 days. These cycles are much longer than the 32 to 34 day cycles reported in Amboseli National Park. Differences may be related to nutritional differences between populations, social differences, or they may reflect underlying genetic differences. (Bentley-Condit and Smith, 1997; Bercovitch, 1987; Hrdy and Whitten, 1987; Melnick and Pearl, 1987)
There is a noticeable menstrual flow for approximately three days per cycle if the female does not conceive. During the period around ovulation, the perineal skin of the female swells, alerting the males to her potentially fertile condition, and enhancing her attractiveness to them. Mating is initiated by the female, who presents her hindquarters to the male. When females are cycling, mating frequency can be from 1 to 6 times per hour. When females become pregnant, they cease to mate at all. Their pericallosal skin turns red as a result of increased blood flow to the region, alerting other members of the group to their reproductive condition. (Hrdy and Whitten, 1987)
Gestation lasts about 175 to 181 days, after which the female gives birth to a single offspring, weighing approximately 854 g. This is significantly smaller than the 1068 g neonates reported for P. anubis. The neonate has a black or reddish coat, depending upon the subspecies. This makes it easy to distinguish neonates from older infants. An infant is completely dependent upon its mother for the first few months, until it begins to eat solid food and is able to walk on its own. Age at independence is difficult to estimate, because even if the mother dies, a young baboon may continue to receive care from adult males, or other female kin. Independence is often listed as the age of weaning.
Females have an interbirth interval of approximately 21 to 27 months. This interval varies geographically, as well as according to maternal age and maternal rank. Interbirth intervals were longer at Tana River than at Amboseli, perhaps in part because the probability of infant survival to 24 months of age was greater. However, in anubis baboons, it has been shown that females who are older or have a higher rank tend to have shorter interbirth intervals, probably because these females experience enhanced nutritional status and are free from harassment by higher ranking females. The interbirth interval is also shorter if an infant dies before weaning. (Altmann, 1980; Bentley-Condit and Smith, 1997; Hrdy and Whitten, 1987; Jolly, 1993; Melnick and Pearl, 1987; Rhine, et al., 1988; Smuts and Nicolson, 1989)
Weaning occurs sometime around 1 year of age. Lactation is a huge cost for adult females, and has been shown to cause a reduction in female weight. Lower ranking and younger females probably take longer to recover adequate body weight to reproduce than do older, dominant females, explaining their longer interbirth intervals. (Altmann, 1980; Bentley-Condit and Smith, 1997; Bercovitch, 1987; Melnick and Pearl, 1987; Smuts and Nicolson, 1989)
The onset of puberty and attainment of adult size is highly variable and is associated with nutrition levels in closely related anubis baboons. The effect of nutrition on growth is so strong that as little as 15 to 16 weeks of dietary variation in newborns can have lasting effects on overall rates of female growth, absolute adult weight, and age at menarche. This may be one reason that differences have been noted in the age of menarche in geographically separated populations. (Strum, 1991)
In yellow baboons, puberty occurs between the ages of 5 and 6 years in females, and is signaled by menarche, or in some cases, first pregnancy. In males, there is greater variation in age at onset of puberty, with sexual maturation occurring between the ages of 4 and 7 years. Between 70 and 97 per cent of males emigrate from their natal troop sometime before reaching sexual maturity. Although females typically spend their entire lives in their natal troops, some transfer of females to new groups has been observed. (Bentley-Condit and Smith, 1997; Melnick and Pearl, 1987; Pusey and Packer, 1987)
Most parental behavior is performed by the female. Females nurse, groom, and play with their offspring. Females express different patterns of infant care, often associated with rank and age. In yellow baboons, higher-ranking females tend to be more "permissive" in their parenting than lower ranking females, who tend to be more nervous and "restrictive," preventing their offspring from moving away from them. Such differences may be related to the amount of harassment females of lower rank are likely to receive. Another difference seen in maternal behavior in this species is that older mothers are known to spend more time in contact or close to their infants and are less likely to terminate bouts of nursing than are younger females. First-time mothers are also likely to reject infants sooner than are experienced mothers. These differences may affect interbirth intervals. (Altmann, 1980; Bentley-Condit, et al., 2001; Melnick and Pearl, 1987)
Males have complex relationships with infants and juveniles, which in some cases may be a form of parental care. Males are known to carry, protect, share food (especially meat), groom, and play with, the offspring of their female friends. Because they are more likely to mate with their female friends than they are with other females, these infants and juveniles are more likely to be their own offspring than are other immature animals within the troop. This behavior, therefore, can be interpreted as paternal. (Melnick and Pearl, 1987; Stein, 1984; Whitten, 1987)
However, it should be noted that the relationship between adult males and these immature animals may be more complex than this. There may be some form of reciprocity involved. Adult males will often carry infants during tense interactions with other adult males. This carrying can be initiated either by the adult male or by the infant. Such contact with an infant during agonistic encounters may have the effect of inhibiting aggression by other males. The favors bestowed upon an infant used as a buffer may therefore be a form a "payback" from the adult male. However, since the tendency to use an infant as an agonistic buffer is related to familiarity with the infant and the probability of paternity, it is impossible to separate the nepotism from the reciprocity of such interactions. (Stein, 1984)
The maximum lifespan of a captive hamadryas baboon is measured at 37.5 years. A captive chacma baboon is reported to have lived 45 years in captivity. Although the lifespan of has not been reported, it is likely to be similar to these two species, although somewhat shorter than these in the wild. (Napier and Napier, 1985; Nowak, 1999)
Yellow baboons are quadrupedal, mainly terrestrial primates. They are highly social animals, with a complex multi-male, multi-female social structure. Members of a troop travel, forage, and sleep together. An average troop may be comprised of 20 to 180 animals. Home ranges averaging 2,408 ha have been reported. The daily range of a troop averages 5,900 m. The movements of a troop may be limited by the availability of appropriate sleeping locations. Because the troop beds down in trees, or on rocks/cliffs, activity of the troop must be coordinated so that one of a set number of sleeping sites can be reached by nightfall. (Melnick and Pearl, 1987; Primate Info Net, 2000)
Males typically emigrate from their natal troops, with 70 to 95 per cent of males emigrating prior to the time that they reach full adult size. Upon settling in a new troop, males must establish themselves in the male dominance hierarchy of that troop. This usually involves aggressive behavior between males, with the "winner" of an encounter establishing dominance over the "loser." Immigrant males may receive the most aggression from males of similar age, as is the case for anubis baboons. For this reason, anubis baboon males have been reported to choose to immigrate into troops containing the fewest like-aged males, and the same factor may play a role when yellow baboon males are choosing a troop in which to settle. (Melnick and Pearl, 1987; Pusey and Packer, 1987; Walters, 1987)
Baboon males apparently leave their natal groups of their own accord. They are not expelled from their natal troop, as some have thought. Emigration of males may be related to sexual attraction to unfamiliar females. Male baboons entering a new troop may direct most of their energy to interacting with females, competing for greater access to estrous females than they had in their natal group. Concomitantly, female baboons apparently prefer to mate with unfamiliar males, often soliciting copulation from new immigrant males. Because of their dispersal pattern, males of hamadryas baboons. (Melnick and Pearl, 1987; Pusey and Packer, 1987)do not maintain long-term bonds with their male kin, as is seen in
The timing of male emigration can vary, and it may be associated with genetic differences between animals. At Amboseli National Park in Kenya, male P. anubis, tend to emigrate as juveniles or subadults. Interestingly, where hybridization between these two species occurs, the hybrids tend to emigrate according to the pattern expressed by the species they most resemble. Males with strongly "anubis" phenotypes tend to emigrate earlier than do hybrid males with strongly "yellow" phenotypes. The reasons for this difference, genetic or social, are not known. (Alberts and Altmann, 2001; Pusey and Packer, 1987)typically leave their natal group around the time that they reach full adult size. However, males the in the closely related species
Whether or not a male is accepted in a group depends greatly on how the females in that troop respond to him. If the females, for whatever reason, do not support the male, and do not wish to mate with him, his transfer into their group may be a lengthy, difficult, and unrewarding process. Females can exhibit some degree of mate choice by accepting or denying males who wish to immigrate into their troop. (Melnick and Pearl, 1987; Smuts, 1987b; Smuts, 1987a)
The dominance rank of females within a troop may affect a number of different aspects of the female’s life. For example, animals with higher dominance rank may have greater access to preferred food resources. This, in turn, may affect their ability to produce healthy offspring, survivorship of young, or the frequency with which they can produce offspring. In addition to having important reproductive consequences, high dominance rank may protect a female from harassment, especially when she has an infant. (Bentley-Condit and Smith, 1997; Bentley-Condit and Smith, 1999; Bentley-Condit, et al., 2001; Nicolson, 1987; Rhine, et al., 1992)
The female dominance hierarchy is not continually challenged by the arrival of new females in the troop, which probably allows for the stability of female dominance relationships over time. Perhaps because relatedness of females within troops is inherently higher than the relatedness of females between troops, female baboons are likely to take the lead in aggressive encounters with other troops of baboons. Females are apparently acting to defend their food resources, and access to those resources in the future, during such encounters. (Melnick and Pearl, 1987)
Female kin behave differently toward one another than do unrelated animals. Females are more likely to aid their kin during disputes than they are to become involved in disputes of unrelated individuals. These relationship can extend over multiple generations, with females aiding not only their own offspring, and aunts aiding nieces, but grandmothers aiding their granddaughters. (Melnick and Pearl, 1987)
Because female (Bentley-Condit and Smith, 1999)are long-lived and philopatric, they are able to develop very complex social relationships. Getting and keeping the right friends in yellow baboon society can have strong implications for maintenance of rank, as well as keeping or losing one’s fetus. One might therefore expect that female baboons would maintain their closest ties with females of similar rank. However, this does not appear to be the case. Rank was not a good predictor of preferred partners for the females at the Tana River National Primate Reserve in Kenya.
Within socially similar cercopithecines, females have been known to establish relationships across matrilines. Females may befriend others who are of similar rank. Also, low ranking females may attempt to gain favor with higher ranking females by providing grooming and other affiliate behaviors. An ally with higher rank may provide a low ranking female with preferential access to scarce food resources, or support during some aggressive encounters. (Bentley-Condit and Smith, 1999)
Home ranges averaging 2,408 ha have been reported. The daily range of a troop averages 5,900 m. (Melnick and Pearl, 1987)
As in all highly social species, communication is varied and complex. Yellow baboons utilize visual signals and gestures, vocalizations, and tactile communication. (Primate Info Net, 2000)
Visual signals include social presenting, in which a female or juvenile displays its hind quarters to a male. It can also be done by a female who has approached another female with her black infant. This submissive signal differs from sexual presenting (which females do to elicit copulation), and is often accompanied by lip smacking. Staring is a threat behavior, the effect of which is enhanced by the differently colored fur in the region of the eye which is revealed when the baboon stares. Eyebrow raising reveals the lighter fur in the area of the eyelid, and is an aggressive gesture. Canine tooth display through a tension yawn is another threatening gesture. It can be directed toward a rival male, a predator, or is performed by lower-raking males toward higher-ranking males who are consorting with estrus females or who possess meat. Male baboons who are close to one another can use tooth grinding to threaten one another. Baboons retreating from high-tension situations use rapid glances to break tension. An adult male who is guarding sometimes sit with his erect penis is plain view. This penile display communicates the male’s presence to other males. (Primate Info Net, 2000)
Teeth chattering and lipsmacking, although not technically vocalizations, are auditory cues of reassurance, often performed by a dominant animal when another is presenting to him. (Primate Info Net, 2000)
Vocalizations made by yellow baboons include a two-phase bark, or "wahoo" call, which adult males direct toward feline predators or toward other males. It is thought to communicate the presence of the male and his arousal. Adult male yellow baboons make grunting vocalizations as a threat. Screeching is common during aggressive encounters, and can be made by any age or sex class. Subadult and adult yellow baboons produce a yakking call when retreating from a threatening animal. This call is often accompanied by a grimace of fear. A shrill bark is produced by all except adult males to indicate alarm, especially due to sudden disturbances. Rhythmic grunting may be produced by all yellow baboons except infants when they wish to signal amicable intentions to another animal. Finally, adult and subadult yellow baboons of both sexes are known to produce a dog-like bark when they become separated from the main part of the troop. (Primate Info Net, 2000)
Tactile communciation is common in cercopithecines. Social grooming is used to reinforce social bonds, as well as to remove parasites and debris from the fur. Social mounting is a reassurance behavior. Anubis baboons also perform a friendly nose-to-nose greeting. (Primate Info Net, 2000)
Chemical communication has not been reported for yellow baboons. However, female anubis baboons are known to produce aliphatic acids when they are sexually receptive. These acids are thought to enhance a female’s sexual attractiveness. Because there is considerable hybridization between anubis baboons and yellow baboons, and because the Ibean form of yellow baboons may have arizen originally through hybridization between typical yellow baboons and anubis baboons, it would be interesting to examine various yellow baboon populations for production of aliphatic acids. (Alberts and Altmann, 2001; Hrdy and Whitten, 1987; Jolly, 1993)
Although generally described as frugivorous, yellow baboons are dietary generalists. they are known to eat pods, grass, sedges, seeds, fruit, roots, leaves, buds, bark, flowers, insects, and meat. They are known hunt and kill rabbits and vervet monkeys. (Melnick and Pearl, 1987; Primate Info Net, 2000; Rhine, et al., 1989; Rhine, et al., 1988)
One feeding adaptation thought to be shared by all baboons is the ability to subsist on a relatively low quality diet. Baboons can subsist on grasses for extended periods of time. This allows them to exploit dry terrestrial habitats, like deserts, semideserts, steppes, and grasslands. (Nowak, 1999)
The feeding behavior of yellow baboons has been heavily studied, especially as it impacts survival of immature animals. Immatures born late in the wet season when the number of foods and food parts eaten is highest have the highest survival to four years of age. This makes sense, as there is ample food for the lactating mother. Survival of immatures is lowest for those born late in the dry season when the number of foods and food parts eaten is the lowest. Survival to two years closely parallels the feeding curves. (Rhine, et al., 1989; Rhine, et al., 1988)
Three predator species are known for yellow baboons. The predation rate varies by population, and is estimated at between 4 and 8 percent per year. Of those who fall victim to predation, about 40% are infants, 30% are juveniles, and 13% are adult females. The remainder are adult males. (Cheney and Wrangham, 1987)
Although yellow baboons typically flee when faced with a potential predator, they have also been reported to respond aggressively to potential predators. They have been observed killing domestic dogs, mobbing smaller carnivores, such as jackals and cheetahs, and have even fought leopards and lions. (Cheney and Wrangham, 1987; Melnick and Pearl, 1987)
There may be a relationship between where in the troop different age or sex classes of baboons travel as it relates to risk of death from predators. However, research on this matter has been largely equivocal. (Cheney and Wrangham, 1987; Rhine and Tilson, 1987)
As predators, yellow baboons may affect the populations of prey items. As prey, they may support predator populations. Baboons may also help to disperse seeds, by passing some through their bodies undigested, or carrying fruits away from trees. They undoubtedly aid in soil aeration from digging for roots and tubers. (Melnick and Pearl, 1987; Nowak, 1999)
Baboons are used heavily in biomedical and behavioral research. They are entertaining creatures enjoyed by zoo visitors and ecotourists. (Williams-Blangero, et al., 1990)
Baboons are not shy creatures, and where they come into contact with humans, they can be problematic. They are known to raid crops, and can bite humans if approached too closely. (Nowak, 1999)
Papio cynocepahlus is not thought to be especially threatened at this time. However, as is true of all primates, it is listed on CITES appendix II.
Anubis baboons (P. anubis) are known to hybridize freely in the wild with yellow baboons, . In the Amboseli national park in Kenya, the amount of reported hybridization between these two species has increased over time. Researchers think that the increasing immigration of anubis males into yellow baboon troops is responsible for the increase noted in hybrid characters. Because the slopes of Mount Kilamanjaro are under increasing agricultural pressure, it is likely that anubis males have no alternative areas into which to emigrate. (Alberts and Altmann, 2001)
The only differences noted in behavior of hybrid animals is that males with anubis-like features (e.g. coarser hair, longer manes, darker coloration, broader chests, and more sharply "broken" tails) tend to emigrate from their natal group as juveniles or subadults, rather than as full adults. This behavior has been seen occasionally in the anubis baboons of the Gombe preserve in Tanzania, but is not known in yellow baboons. (Alberts and Altmann, 2001)
The hybridization between anubis and yellow baboons seems to have a long history. Interestingly, the Ibean form of yellow baboon, which has coarser hair than typical yellow baboons, a more pronounced mane, and other somewhat "anubis-like" features, is thought by some researchers to be evidence of the historical influx of anubis genes into yellow baboon populations. (Alberts and Altmann, 2001; Jolly, 1993)
Nancy Shefferly (author), Animal Diversity Web.
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
uses sound to communicate
living in landscapes dominated by human agriculture.
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
flesh of dead animals.
Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.
uses smells or other chemicals to communicate
ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates
humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
union of egg and spermatozoan
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
an animal that mainly eats all kinds of things, including plants and animals
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
scrub forests develop in areas that experience dry seasons.
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
one of the sexes (usually males) has special physical structures used in courting the other sex or fighting the same sex. For example: antlers, elongated tails, special spurs.
associates with others of its species; forms social groups.
digs and breaks up soil so air and water can get in
uses touch to communicate
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
breeding takes place throughout the year
Alberts, S., J. Altmann. 2001. Immigration and hybridization patterns of yellow and anubis baboons in and around Amboseli, Kenya. American Journal of Primatology, `53: 139-154.
Altmann, J. 1980. Baboon Mothers and Infants. Chicago: The University of Chicago Press.
Bentley-Condit, V., T. Moore, E. Smith. 2001. Analysis of infant handling and the effects of female rank among Tana River adult female yellow baboons (Papio cynocephalus cynocepahlys) using permutation/randomization tests. American Journal of Primatology, 55: 117-130.
Bentley-Condit, V., E. Smith. 1999. Female dominance and female social relationships among yellow baboons (Papio hamadryas cynocephalus). American Journal of Primatology, 47: 321-334.
Bentley-Condit, V., E. Smith. 1997. Female reproductive parameters of Tana River yellow baboons. International Journal of Primatology, 18/4: 581-595.
Bercovitch, F. 1987. Female weight and reproductive condition in a population of olive baboons (Papio anubis). American Journal of Primatology, 12: 189-195.
Cheney, D., R. Wrangham. 1987. Predation. Pp. 227-239 in B Smuts, D Cheney, R Seyfarth, R Wranghams, T Struhsaker, eds. Primate Societies. Chicago: The University of chicago Press.
Disotell, T. 2000. Molecular systematics of the Cercopithicidae. Pp. 29-56 in P Whitehead, C Jolly, eds. Old World Monkeys. Cambridge, UK: Cambridge University Press.
Dunbar, R. 1987. Demography and reproduction. Pp. 240-249 in B Smuts, D Cheney, R Seyfarth, R Wrangham, T Struhsaker, eds. Primate Socieites. Chicago: The University of Chicago Press.
Eldredge, N. 1993. What, if anything, is a species?. W Kimbel, L Martin, eds. Species, Species Concepts, and Primate Evolution. London: Plenum Press.
Groves, C. 2001. Primate Taxonomy. Washington, D.C.: Smithsonian Insitution Press.
Groves, C. 2000. The Phylogeny of the Cercopithecoides. Pp. 77-100 in P Whitehead, C Jolly, eds. Old World Monkeys. Cambridge, UK: Cambridge University PRess.
Hamilton III, W., J. Bulger. 1992. Facultative expresion of behavioral differences between one-male and multimale savanna baboon groups. American Journal of Primatology, 28: 61-71.
Harvey, P., R. Martin, T. Clutton-Brock. 1987. Life histories in comparative perspective. Pp. 181-196 in B Smuts, D Cheney, R Seyfarth, R Wrangham, T Struhsaker, eds. Primate Societies. Chicago: The University of Chicago Press.
Hrdy, S., P. Whitten. 1987. Patterning of sexual activity. Pp. 370-384 in B Smuts, D Cheney, R Seyfarth, R Wrangham, T Struhsaker, eds. Primate Socieities. Chicago: The University of Chicago PRess.
Jolly, C. 1993. Species, subspecies, and baboon systematics. Pp. 67-107 in W Kimbel, L Martin, eds. Species, Species Concepts, and Primate Evolution. New York: Plenum Publishing.
Jolly, C., P. Whitehead. 2000. Old world monkeys: Three decades of development and change in the study of the Cercopithicoidea. Pp. 1-28 in P Whitehead, C Jolly, eds. Old World Monkeys. Cambridge, UK: Cambridge University Press.
Jolly, C., J. Phillips-Conroy. 2003. Testicular size, mating system, and maturation schedules in wild anubis and hamadryas baboons. International Journal of Primatology, 24/1: 125-142.
Kummer, H. 1968. Social Organisation of Hamdryas Baboons. A Field Study. Basel and Chicago: Karger, and University Press.
Masters, J. 1993. Primates and paradigms: Problems with the identification of genetic species. Pp. 43-64 in W Kimbel, L Martin, eds. Species, Species Concepts, and Primate Evolution. New York: Plenum Publishing.
Mayr, E. 1942. Systematics and the Origin of Species. New York: Columbia University Press.
Melnick, D., M. Pearl. 1987. Cercopithecines in multimale groups: Genetic diversity and population structure. Pp. 121-134 in B Smuts, D Cheney, R Seyfarth, R Wrangham, T Struhsaker, eds. Primate Societies. Chicago: The University of Chicago Press.
Napier, J., P. Napier. 1985. The natural history of the primates. Cambridge, Massachusetts: The MIT Press.
Nicolson, N. 1987. Infants, mothers, and other females. Pp. 330-342 in B Smuts, D Cheney, R Seyfarth, R Wrangham, T Struhsaker, eds. Primate Societies. Chicago: The University of Chicago Press.
Nowak, R. 1999. Walker's Mammals of the World, Sixth Edition. Baltimore: The Johns Hopkins University Press.
Oates, J. 1987. Food distribution and foraging behavior. Pp. 197-209 in B Smuts, D Cheney, R Seyfarth, R Wrangham, T Struhsaker, eds. Primat Societies. Chicago: The University of Chicago Press.
Phillips-Conroy, J., C. Jolly, P. Nystrom, H. Hemmalin. 1992. Migration of male hamadryas baboons into anubis groups in the Awash National Park, Ethiopia. International Journal of Primatology, 12/4: 455-475.
Primate Info Net, 2000. "Primate Info Net" (On-line). Yellow Baboon (Papio cynocephalus). Accessed July 14, 2003 at http://www.primate.wisc.edu/pin/factsheets/papio_cynocephalus.html.
Pusey, A., C. Packer. 1987. Dispersal and philopatry. Pp. 250-266 in B Smuts, D Cheney, R Seyfarth, R Wrangham, T Struhsaker, eds. Primate Societies. Chicago: The University of Chicago Press.
Rhine, R., G. Norton, J. Rogers, S. Wasser. 1992. Secondary sex ratio and maternal dominance rank among wild yellow baboons (Papio cynocephalus) of Mikumi National Park, Tanzania. American Journal of Primatology, 27: 261-273.
Rhine, R., G. Norton, G. Wynn, . Wynn. 1989. Plant feeding of yellow baboons (Papio cynocephalus) in Mikumi National Park, Tanzania, and the relationship between seasonal feeding and immature survival. International Journal of Primatology, 10/4: 319-341.
Rhine, R., R. Tilson. 1987. Reactions to fear as a proximate factor in the sociospatial organization of baboon progressions. American Journal of Primatology, 13: 119-128.
Rhine, R., S. Wasser, G. Norton. 1988. Eight-year study of social and ecological correlates of mortality among immature baboons of Mikumi National Park, Tanzania. American Journal of Primatology, 16: 199-212.
Rogers, J. 2000. Molecular genetic variation and population structure in Papio baboons. Pp. 57-76 in P Whitehead, C Jolly, eds. Old World Monkeys. Cambridge, UK: Cambridge University Press.
Sapolsky, R., J. Ray. 1989. Styles of dominance and their endocrine correlates among wild olive baboons (Papio anubis). American Journal of Primatology, 18: 1-13.
Sapolsky, R. 1996. Why should an aged male baboon ever transfer troops?. American Journal of Primatology, 39. Accessed (Date Unknown) at 149-157.
Smuts, B. 1987. Gender, aggression, and influence. Pp. 400-412 in B Smuts, D Cheney, R Seyfarth, R Wrangham, T Struhsaker, eds. Primate Societies. Chicago: The University of Chicago Press.
Smuts, B. 1987. Sexual competition and mate choice. Pp. 385-399 in B Smuts, D Cheney, R Seyfarth, R Wrangham, T Struhsaker, eds. Primate Societies. Chicago: The University of Chicago Press.
Smuts, B., N. Nicolson. 1989. Reproduction in wild female olive baboons. American Journal of Primatology, 19: 229-246.
Stammbach, E. 1987. Desert, forest, and montain baboons: Multilevel societies. Pp. 112-120 in B Smuts, D Cheney, R Seyfarth, R Wrangham, T Struhsaker, eds. Primate Societies. Chicago: The University of Chicago Press.
Stein, D. 1984. The Sociobiology of Adult Male and Infant Baboons. Norwood, NJ: Ablex Publishing.
Strum, S. 1991. Weight and age in wild olive baboons. American Journal of Primatology, 25: 219-237.
Swedell, L. 2002. Affiliation among females in wild hamadryas baboons (Papio hamadryas hamadryas). International Journal of Primatology, 23/6: 1205-1225.
Szalay, F. 1993. Species concepts: The tested, the untestable, and the redundant. Pp. 27-41 in W Kimbel, L Martin, eds. Species, Species Concepts, and Primate Evolution. New York: Plenum Press.
Thorington, R., C. Groves. 1970. An annotated classification of the Cercopithecoidea. Pp. 629-647 in J Napier, P Napier, eds. Old World Moneys. New York: Academic Press.
Virgin, Jr., C., R. Sapolsky. 1997. Styles of male social behavior and their endocrine correlates among low-ranking male baboons. American Journal of Primatology, 42: 25-39.
Walters, J. 1987. Transition to Adulthood. Pp. 358-369 in B Smuts, D Cheney, R Seyfarth, R Wrangham, T Struhsaker, eds. Primate Societies. Chicago: The University of Chicago Press.
Walters, R., R. Seyfarth. 1987. Conflict and cooperation. Pp. 306-317 in B Smuts, D Cheney, R Seyfarth, R Wrangham, T Struhsaker, eds. Primate Societies. Chicago: The University of Chicago Press.
Whitten, P. 1987. Infants and adult males. Pp. 343-357 in B Smuts, D Cheney, R Seyfarth, R Wrangham, T Struhsaker, eds. Primate Societies. Chicago: The University of Chicago Press.
Williams-Blangero, S., J. Vandenberg, J. Blangero, L. Konigsberg, B. Dyke. 1990. Genetic differentiation between baboon subspecies: Relevance for biomedical research. American Journal of Primatology, 20: 67-81.
Zinner, D., F. Pelaez. 1999. Verreaux's eagles (Aquila verreauxi) as potential predators of hamadryas baboons (Papio hamadryas hamadryas). American Journal of Primatology, 47: 61-66.
Zinner, D., F. Pelaez, F. Torkler. 2001. Group composition and adult sex-ratio of hamadryas baoons (Papio hamadryas hamadryas) in central Eritrea. International Journal of Primatology, 22/3: 415-429.
Zinner, D., T. Deschner. 2000. Sexual swellings in female hamadryas baboons after male take-overs: "Deceptive" swellings as a possible female counter-strategy against infanticideticide. American Journal of Primatology, 52: 157-168.